Many individuals die every year from "cardiac electrical death." The typical sequence is that the person has a congenital electrical problem or underlying organic heart disease for years. This can suddenly cause the the lower part of the heart ("ventricles") to race out of control (ventricular "tachycardia") with an inefficient excessive rate. The ventricular tachycardia can then rapidly deteriorate into an electrical storm (ventricular "fibrillation") in which there is no pumping action. Unconsciousness occurs within 30 seconds and death follows in minutes.
There are three main therapies for such patients. The first therapy is antiarrhythmic drugs. Unfortunately, these have many side effects. The second therapy is the implantation of a defibrillator. The implantable defibrillator is designed to sense the ventricular tachycardia or ventricular fibrillation and deliver appropriate pacing pulses or a high energy defibrillation shock to the heart to restore normal ("sinus") rhythm. The third therapy is "ablation" in which the unstable heart cells, responsible for the arrhythmia, are destroyed through freezing or burning.
Because of the side effects of the drugs and the surgical risks involved with the implantable defibrillator or ablation therapy, patients are examined very carefully before receiving their therapies. Their propensity for ventricular tachycardia or ventricular fibrillation is determined by attempting to "induce" one of these conditions. A current carrying catheter is introduced through the leg and one end is moved about in the ventricle. Electrical pulses are then introduced into the ventricle in an attempt to destabilize the heart. If either a ventricular tachycardia or a ventricular fibrillation (collectively referred to as a ventricular arrhythmia) occurs, the patient is said to be "inducible" and the appropriate therapies are then prescribed.
The inducibility study is also referred to as an electrophysiological study or a PVS (programmed ventricular stimulation) study. While the inducibility study allows lifesaving therapies, it also has pain and risks of death associated with it. Hence there is a need for a noninvasive and safe means of predicting inducibility.